So many things went wrong last Jan. 29 to contribute to the collision between an airliner and a U. S. Army helicopter that killed 67 people that the National Transportation Safety Board isn't likely to identify a single cause at its hearing Tuesday So many things went wrong last Jan.

Add Yahoo as a preferred source to see more of our stories on Google. Aviation safety campaigners in the United States say they have evidence a plane that crashed in India last year had previously suffered a series of technical failures, including a fire.